The hot and cold water mixing device such as a hot and cold water mixing faucet is formed therein with a hot water passage and a cold water passage, through which hot water and cold water flow, respectively, and at the same time, is formed with a mixing chamber therein for mixing the hot and cold water introduced and with a mixed water passage through which the mixed water is delivered, in order to mix the hot and cold water supplied from a hot water supply source and a cold water supply source, respectively, to deliver the mixed water having a desired temperature.
These fluid passages have hitherto been formed by providing a body (casing) of a faucet made by casting, with partition walls therein, through integral moulding (for example, refer to JPB-58(1983)-40060). The body casing made by casting has an advantage in that the fluid passages therein can be formed in relatively free forms; however, there is a problem in that the body casing becomes large in configuration and also heavy in weight.
A hot and cold water mixing device has, therefore, been developed in which the body casing is composed of a hollow metal pipe material in place of the body casing made by casting, and a hollow inner casing is inserted into the pipe material, fluid passages being formed in the gap between the pipe material and the inner casing (U.S. Pat. No. 4,610,393).
In the hot and cold water mixing device comprising the pipe material and the inner casing inserted therein, the pipe material is provided with openings which communicate with a hot water supply passage, a cold water supply passage and a mixed water delivery passage, and further, the inner casing is also provided with water holes which communicate with the hot water supply passage, water supply passage and mixed water delivery passage. Further, the openings of the pipe material and the water holes of the inner casing are disposed with the respective passages corresponding to the hot water supply passage, cold water supply passage and mixed water delivery passage being close to each other, and seal members (O-rings) are provided between the respective openings and the water holes in the circumferential direction, so that the hot water passage, mixed water passage and cold water passage are formed in a divided manner in the axial direction of the pipe material.
In the inner casing of this hot and cold water mixing device is incorporated an opening and closing valve for adjusting the delivery amount of the mixed water and a mixing valve having an automatic temperature-regulating function for automatically regulating the mixing ratio of hot and cold water in the relation corresponding to a set temperature.
Accordingly, the hot water, which has flowed into the inner casing through the opening and the water hole communicating with the hot water supply passage, and the cold water, which has flowed into the inner casing through the opening and the water hole communicating with the cold water supply passage, are passed through the mixing valve and mixed there in a suitable mixing ratio, and then the mixture is delivered from the mixed water delivery passage by the operation of the opening and closing valve.
The hot and cold water mixing device using the pipe material and inner casing has an advantage in that the dimension of the external form thereof is made smaller and reduced in weight, as compared with that using the body casing made by casting.
However, since a plurality of O-rings are mounted on the outer peripheral surface of the inner casing to form the hot water passage, mixed water passage and cold water passage in a divided manner from one end to the other end of the inner casing, the hot and cold water mixing device comes to be parted into three distributions of temperature--a high temperature part, a moderate temperature part and a low temperature part.
This results in losing the thermal balance of the entire hot and cold water mixing device, thereby causing the deformation of the parts due to the difference in thermal expansion, the deterioration of the high temperature parts, and a decrease in precision. Further, since the hot water at a high temperature flows over the entire circumference at one end of the body of the mixing faucet, a portion of the pipe material at the side of an operator comes to be a high temperature. This is very dangerous particularly in the case where the device is used in a bathroom.
Accordingly, a proposal is made to solve the problem of the thermal balance of the entire hot and cold water mixing device as mentioned above while maintaining the advantage of the pipe material being used as the body casing (U.S. Pat. No.4,381,073).
According to such a proposal, the hot water supplied from the hot water supply passage into the pipe material flows directly into the inner casing without flowing in the circumferential direction of the pipe material and, simultaneously, the cold water supplied from the water supply passage once flows into the inside of the casing and, thereafter, flows out again into the gap between the pipe material and the inner casing to cover the inner casing with the cold water in a greater part of the outer circumference, thereby preventing the outer surface of the pipe material from being locally heated to bring about a danger and preventing a significant thermal imbalance from being caused over the entire hot and cold water mixing device.
The hot and cold water mixing device described in U.S. Pat. No. 4,381,073 solves the problem of thermal imbalance utilizing an advantage of the pipe material being used for the body casing; however, there is a problem in that the construction of the inner casing becomes extremely complicated and, simultaneously, an adjustment in the offsets between the openings of the pipe material and the water holes of the inner casing is difficult; so, the strict accuracy of finishing and assembly of the component parts is required.
Namely, in the hot and cold water mixing device described in FIG. 1 of U.S. Pat. No.4,381,073, since the hot and cold water passages are formed by a plurality of O-rings mounted on the outer circumference of the inner casing, and the mixed water passage is formed by two O-rings mounted on the inner circumference of the inner casing, the water supplied from a water supply source flows through the complicated flow passages so that it flows into the inner casing at one time and, thereafter, is moved through the insides of the O-rings in the axial direction, and flows out again into the gap between the pipe material and the inner casing outwardly in the radial direction.
This increases the number of the parts constituting the water passages and also makes the construction of the assembly of these parts extremely complicated. Moreover, it is necessary to further dispose one more hollow casing within the inner casing to constitute the mixing water passage. In addition, the hot water flows over the entire circumference of the pipe material although it flows partially and, therefore, the problem of the danger of a scald has not yet been solved.
In the hot and cold water mixing device described in FIG. 2 of U.S. Pat. No. 4,381,073, as stated above, since the hot water passage is not formed over the entire circumference, the problem of the danger of a scald is solved. However, the water passages are complicated, like those described above, and the number of parts which constitute the mixing device is increased. For this reason, there is a problem in that the strict accuracy of finishing and assembly of each component is required, and therefore, the finishing and assembly of the hot and cold water mixing device are difficult.
On the other hand, there is the case where forming the body casing by casting or forging is necessary on the basis of the hot and cold water mixing device being required to have a feeling of quality and configuration which are adapted to the atmosphere in a place of installation. In such a case, machining such as cutting, polishing and the like must be carried out in the interior of the body casing.
Further, a reduction in noise, vibration and the like produced when the hot and cold water mixing device is used, is required.
The present invention has been made taking such points into consideration and aims at providing a hot and cold water mixing device which is easy to produce and which has a thermal insulation property.
Further, the present invention aims at providing a hot and cold water mixing device which allows the vibration and noise during the use of the device to be prevented.